Chimico & Petrolchimico

When analyzing hydrocarbon impurities in propylene by ASTM D2712, using an Rt-Alumina BOND Na2SO4 PLOT column instead of a packed column setup provides the greatest degree of resolution in the least amount of time. (PDF - 0kB)

Restek’s Rtx-Volatile Amine column is specifically designed for GC analysis of volatile amines in challenging matrices. The stable bonded phase is highly retentive and selective for volatile amines to ensure good chromatographic separations and peak shapes. In addition, the column is very robust and able to withstand repeated exposure to harsh sample matrices, such as water.

The high temperatures required to analyze glycerol and glycerides as contaminants in biodiesel can result in shorter column lifetimes and more instrument downtime. Metal MXT-Biodiesel TG columns are more durable and last longer than their fused silica column counterparts, making them a better choice for labs wanting to minimize downtime. As demonstrated here, MXT-Biodiesel columns meet method EN 14105 (2011) performance requirements and provide excellent chromatographic results for biodiesel testing.

Volatile amines, such as monomethylamine, diethylamine, and triethylamine, are widely used in the petrochemical industry, but are prone to poor peak shape and difficult to analyze. Low levels of volatile amines can now be accurately reported using new Rtx-Volatile Amine columns due to high column inertness.

Accurate analysis of biodiesel FAME in jet fuel is critical for ensuring that contamination levels do not exceed allowable limits. Method IP 585 is commonly used for this analysis and here we perform the method using a Stabilwax column and GC-MS in SIM mode. Method calibration curve criteria were met and good recoveries of the total FAME content in jet fuel were obtained.

Polar columns were evaluated for the analysis of fatty acids methyl esters (FAMEs) in finished B100 biodiesel according to method EN 14103 (2011). Using Restek’s Pro EZGC chromatogram modeler, a high cyano phase Rt-2330 column and a polyethylene glycol phase FAMEWAX column were compared. The modeling software predicted an unacceptable coelution between the internal standard (C19:0 FAME) and FAME C18:2 when using the Rt-2330 column. However, the modeler also predicted that the FAMEWAX column would separate all the compounds of interest, which was demonstrated empirically. In addition, the results on the FAMEWAX column showed excellent repeatability for both total FAMEs and the linolenic acid methyl ester component.

When testing for impurities in ethylene using ASTM D6159-97, the combination of an Rt-Alumina BOND column coupled to an Rtx-1 column provides the best resolution of the most common hydrocarbon contaminants. (PDF - 0kB)

Impurity analysis of 1,3-butadiene on an Rt-Alumina BOND/MAPD column results in good separation of both light polar impurities (methyl acetylene, propadiene) and 4-vinylcyclohexene, a heavier contaminant that often requires testing on a second column.

We challenged our Rtx-Biodiesel column with analysis for glycerin in biodiesel according to method ASTM D-6584-00. Excellent linearity was established for glycerin, triolein, monolein, and diolein, with r2 values exceeding the method criteria for all compounds. Mono-, di-, and triglycerides resolved well from other compounds in B100 biodiesel oil. Column performance was strong at high temperatures, with low bleed even at 380°C. An Alumaseal connector and guard column were used to extend column life.

Trace levels of sulfur compounds are separated and quantified by using an Rtx-1 capillary column or an Rt-XLSulfur micropacked column. The latter column is a specially deactivated porous polymer in Sulfinert-passivated stainless steel tubing.

The current helium shortage has severely impacted gas chromatographers who are finding that helium has become significantly more expensive and is not always available when needed. This article explores the benefits and considerations of replacing helium with hydrogen carrier gas.

This flyer includes data demonstrating the performance of recommended GC columns for the analysis of total glycerin, fatty acid methyl esters (FAMEs), and residual methanol in biodiesel. Features a comparison of metal and fused silica columns. (PDF - 0kB)

Virtually unlimited in supply—but only available from Restek—new DiatoSorb-W diatomaceous earth offers a reliable alternative for packed column users. After years of dealing with supply shortages and inconsistent product quality, analysts who depend on diatomaceous earth columns now have a reliable new source. Restek now uses DiatoSorb-W as the exclusive replacement to the diatomaceous earth that was previously used in our standard and Silcoport W GC packed columns lines. All DiatoSorb-W material undergoes rigorous quality testing to ensure high purity and dependable performance. DiatoSorb-W material is available in acid-washed (WAW), non-acid washed (WNAW), and high-performance (WHP) varieties.

Robust Rtx-DHA columns are highly stable and can be run with hydrogen carrier gas under accelerated conditions. The hydrogen-based method for detailed hydrocarbon analysis shown here is twice as fast as traditional approaches, which allows labs to process samples faster and make more profitable decisions during product blending.

Comprehensive 2D GC, also known as GCxGC, is a powerful technique with a great deal of potential for improving separations of complex petroleum and petrochemical samples that contain hundreds—or even thousands—of components. While GCxGC is still considered emerging technology and is used primarily in research and development labs, it has undergone significant growth in the past few years.

The high temperatures required for biodiesel analysis by gas chromatography present a considerable challenge to analytical columns. Fused silica columns, even those rated for high-temperature tolerance, breakdown relatively quickly. Restek’s new MXT-Biodiesel columns are more stable up to 430°C and offer excellent chromatography for glycerides. These columns are available in two configurations: factory-coupled to a 0.53mm retention gap, or with a built-in, leak-proof Integra-Gap retention gap.

Rt-Alumina BOND/CFC columns provide high retention and high selectivity for volatile halogenated hydrocarbons, without the activity that is usually observed with alumina adsorbents. Chlorofluorocarbon analysis, in particular, can benefit from this new technology.

Restek's new D3606 column set outperforms TCEP columns for gasoline testing. The D3606 set has higher thermal stability and reliably resolves benzene from ethanol, resulting in more accurate quantitation.

This 2-column set for modified ASTM Method D3606-10 completely resolves benzene from ethanol in reformulated fuels containing ethanol. The aromatic compounds also are fully separated and can easily be quantified using sec-butanol as an internal standard. (PDF - 0kB)

A Restek PLOT column can be your best solution for difficult separations of gaseous analytes. Rt-Msieve 5A PLOT columns offer fast, efficient separation of argon/oxygen, hydrogen/helium, and other permanent gases, including permanent gases in refinery or natural gas. You can make difficult separations without subambient temperatures, e.g.: separate oxygen from argon to baseline in approximately 4 minutes.

Refinery and natural gas samples often contain trace amounts of sulfur- and mercury-containing compounds, which can interfere with reactions, poison catalysts in petrochemical processes, and damage equipment. Because these compounds quickly react with stainless steel surfaces, accurate determination of these compounds is impossible when samples are collected and stored in untreated sample cylinders. Restek's Siltek and Sulfinert passivation techniques bond an inert layer into the surface of stainless steel, preventing active compounds from reacting with or adsorbing to the steel.

The results of a simulated distillation analysis are vitally important to the operation of refineries globally. For the analysis of petroleum samples within the boiling point range from 55.5 ˚C to 538 ˚C, ASTM D2887 is a standard method that has been accepted and is used industry-wide. This application note will demonstrate how a creative use of the Restek GC Accelerator oven insert kit can permit analysts using Agilent 6890/7890 GCs with 100/120 V ovens to successfully migrate from D2887’s slower Procedure A conditions to the accelerated Procedure B conditions without new instrumentation or software, resulting in a 9-minute analysis time that meets all method requirements.

ASTM Method D2887 now allows for alternate carrier gases, so hydrogen or nitrogen can replace helium carrier gas for simulated distillation. Here, we show that with an MXT-1HT SimDist column and Restek’s EZGC online method translator existing methods using helium can be easily converted to either hydrogen or nitrogen carrier gas. Because retention times are preserved with proper method translation, there are minimal changes to peak identification tables which significantly simplifies method validation.

Most analysts still use traditional packed columns for light hydrocarbon analysis, but many adsorbents are also available in micropacked column formats. Micropacked columns are a good alternative when both efficiency and sample loadability are desired.